Mobile computing devices (e.g., smart phones, tablets) with touch screens are used all around the world for an ever increasing number and type of applications. Characters in some languages (e.g., English) are easier to input via a touch screen than are characters from other languages (e.g., Chinese, Japanese). A touch screen is an electronic visual display that can both display items and detect the presence and location of a touch. The touch may be made by a finger, stylus, or other item. A touch screen facilitates interacting directly with what is displayed, rather than interacting indirectly with some other device (e.g., keypad, mouse). Touch screens are used in computers, printers, navigation devices, microwaves, televisions, tablet computers, and other devices.
Practical keypads for inputting English characters through a touch screen device exist. These practical keypads may simply replicate a conventional QWERTY keyboard where there is a one-to-one correspondence between a key on the keyboard and a character. A typical English keyboard may have around eighty keys, a shift key that can effectively double the number of characters, and a control key that can double the number of characters again or allow inputting special characters. Touch screen devices may mimic the shift key and control key, and may also have additional screens of characters that can be input. While this may be practical for English, which has a small closed set of characters, this may not be practical for Chinese characters since there may be over one hundred thousand Chinese characters. Additionally, new Chinese phrases are still being created.
Chinese characters may be, for example, logograms. There are different types of Chinese characters. For example, there are phono-semantic compounds, ideogrammic compounds, pictograms, ideograms, and others. Phono-semantic compounds may also be referred to as radical-phonetic characters. Phono-semantic compounds form the vast majority of Chinese characters. Phono-semantic compounds combine a rebus with a determinative and thus combine a phonetic element (e.g., character with approximately the correct pronunciation) with a radical (e.g., limited number of determinative characters that supply an element of meaning): The radical is usually on one side (e.g., left side), while the phonetic is on the other side (e.g., right), (e.g., = “water”+ mù). The semantic and phonetic elements may also be stacked, (e.g., = “plant”+ c{hacek over (a)}i). Phono-semantic compounds may account for over 80% of Chinese characters. Therefore, there may be over eighty thousand phono-semantic compounds. It is therefore difficult, if even possible, to imagine a one-to-one correspondence keyboard similar to the QWERTY keyboard that could efficiently handle eighty thousand characters.